In the thermal treatment of coal under the exclusion of air in a coke oven, coke oven crude gas is produced which is cooled by means of water droplets [trickling water] in a crude gas condenser to about 80° C. and is saturated with water vapor. As a result, about 20% of the naphthalene entrained with the coke oven crude gas is bound up in tar in the liquid phase. The remaining 80% of the naphthalene is then condensed in an indirect crude gascooling together with tarry aqueous components in a precooler. This condensate is initially fed to the crude gas condenser, there heated to about 80° C. and supplied to a tar separation in which the separation of crude tar from cooled water is effected. The naphthalene contained in the crude tar is recovered from the crude tar in highly expensive processes from a process technology view point. Initially in a distillation of the tar a naphthalinol is produced is then subjected to crystallization in which the crude naphthalene is deposited out to recover pure naphthalene, further processes like chemical reactions, (for example with sodium hydroxide and sulfuric acid) are required or the raw naphthalene is distilled again.